This invention relates generally to the extraction process and more particularly, to a process and a reactor for the continuous extraction of vegetable-fibre material such as wood chips. The process comprises treating the material with organic solvents at elevated temperatures. The vegetable-fibre material is first impregnated with organic solvents in an impregnating device and then passed to a reactor.
In the past, the sulphate process or the sulphite process were used to produce cellulose which was processed further into paper. One of the most important disadvantages of these processes was the resultant heavy pollution caused by the thus produced waste water and waste-gases, especially from the standpoint of sulphur-content.
More recently, as a result of this disadvantage, various processes for continuous extraction of vegetable-fibre material have been developed, in which no sulphur-containing compounds are used. In addition, other compounds contained in the vegetable fibres, may also be recovered in addition to cellulose. Such other compounds include, for example, lignin and hemicellulose. Such a process is described in German Offenlegungsschrift No. 28 55 052. These processes have been very complicated and expensive.